[quote=Br. Rich SFO]Today many people are under the impression that in order to sin one must willfully and knowingly committ a sin. However a sinful act is a sinful act objectively speaking.
Brother Rich, you are referring to the concepts of material sin and formal sin.
Material sin is an act that is objectively wrong. As distinguished from formal sin, it is committed without full knowledge and/or consent, and therefore, one is not culpable before God.
Formal sin occurs when a person commits an act which either is objectively wrong, or is thought to be objectively wrong. In either case, the person is guilty in his conscience before God.
For example: You don’t know that your friend’s shoulder is injured, and you give him a friendly slap on the back. This causes him terrible pain, but he doesn’t blame you because you had no idea that the friendly backslap would hurt him. This is analogous to material sin.
Another example: You think your friend’s shoulder is injured, and, because you are angry with him and wish to hurt him, you give him a “friendly” slap on the back. Unbeknownst to you, his shoulder has healed, and you cause him no pain. You have committed a formal sin here, because you intended your “friendly” slap to have a painful result, even though it didn’t. If your friend figures this out, he will rightfully be angry with you.
Final example: The most common is the sin you are aware of and consent to. You know your friend’s shoulder is injured, you want to hurt him, and you slap his back, causing pain. It’s all out in the open, and he has every right to blame you for his pain. This is also formal sin.
The sins that you intend to commit, the formal sins, are the ones for which you will be held responsible, and which you must confess if they involve grave matter. The sins you do not intend to commit are not imputed to you. But, of course, a sincere “I’m so sorry; I never meant to hurt you” is always appreciated both by the person you have harmed and by God.